Modern residential forced-air heating and cooling systems rely on electricity to supply heating and cooling air. The main drawback of such systems is failure during electrical power outages. Modern compressor type air conditioning/cooling systems also use enormous amounts of electricity, which increases the likelihood of power grid failures, has a negative impact on the environment, and costs consumers money.
Space heaters are a common supplement, alternative, or backup to forced-air heating systems, but currently account for many fatal house fires, killing over 600 people and causing close to a billion dollars in damage annually.
Electric fans are the primary alternative to modern air conditioning systems, but they also fail during power outages, and it is not uncommon for vulnerable people to die from heat stroke.
Hydraulic-powered forced air heating and cooling apparatus is known for vehicle heating and cooling systems, with a fan driven by a hydraulic motor blowing air across a fluid-filled radiator. Examples include those shown in U.S. Pat. No. 3,934,644 to Johnston and U.S. Pat. No. 6,158,216 to Buschur et al. Such systems do not appear to have been commonly used, however, even in the limited field of vehicle heating and cooling systems.
Hydraulically (usually water) driven fans are known for outdoor industrial uses, for example to cool heavy equipment at natural gas wells. It is also believed that water-driven fans were used for direct forced-air residential cooling in the 19th century, before household electricity was known or commonplace.